[Elecraft] K1 question...

[Dave KQ3T]

Hi Tom,

Both varieties will produce the DC voltages you need (as would a few 
batteries). For your purposes, the differences between the two types may 
not matter.

Linear power supplies use a conventional transformer to convert line 
voltage (117vac) to a lower voltage (typically 15-18vac), which is then 
rectified by diodes, filtered by capacitors and (usually) controlled by 
a voltage regulator to 13-14 volts DC. Unfortunately, as the current 
goes up, the size of the transformer (which usually contains an iron 
core) goes up as well; a 20 amp 12V linear power supply might weigh 15 
lbs or more.

Switching power supplies generate a high frequency AC voltage, which 
does away with the need for the heavy transformer. So switching supplies 
tend to be lighter than linear supplies for the given amount of current 
produced. The disadvantage is that the high frequency AC can, in poor 
designed/shielded supplies, generate "hash" that can be heard in your 
receiver.

QST has tested a number of switching power supplies recently, you might 
check to see if the supplies you're considering have been evaluated.

73,
Dave KQ3T

Thomas R. Hauff wrote:
> Hi y'all!
>
> I have noted that most of the posts in the elecraft reflector are about the
> K3. I hope this isn't out of line.
>
> I bought a K1 awhile back because it was billed as a great first-time
> builder's kit. As one of those first-time builders,  I suppose I'd agree,
> but I've run into a few rather basic questions and I'm undoubtedly driving
> Gary up the wall with them. I'm a rank beginner on all things electronic I'm
> afraid. He's set me the task of building an RF probe (which I'm getting to)
> and told me to get a signal generator as well. 
>
> I need to do the signal tracing the manual suggests (Appendix E, p5)  and
> wanted to build the signal generator shown in schematic on that page. I have
> the KFL1-4 board with 17, 20, 30 and 40 meters and am only hearing signals
> on the 40 meter band. I thought I'd build the signal generator with a switch
> to change between crystals. 
>
> I'm looking for some advice: 
>
>  
>
> I have one power supply (a Samlex SEC-1235M) and I guess I'll need another
> power source for the signal generator. As I looked at the Samlex site
> (http://www.universal-radio.com/CATALOG/hamps.html), I saw both linear and
> switching power supplies. Does it matter which kind I get? Any other
> suggestions for inexpensive options? 
>
>  
>
> I suppose I'll stop with one question for now.
>
> Thanks hams!
>
>  
>
> Tom (WB7RTE)
>
>